Im kind of new to cars but theres one thing thats been bugging me since joining this forum.... How does HP translate into RWHP? I thought if a rear wheel drive car had 500 horse power, it would also have 500 rear wheel horse power but i guess not so much?

there are losses in the drive train from friction and momentum losses.

it isnt a set percentage exactly, but it is close, if you figure it that way.

friction coeficients of the engine, transmission, wheel bearings, differentials, universal joints all add up. things like tire friction losses. the higher rate if accleration that you try to accelerate an object, the more energy it takes to accelerate it.

the drivetrain can be considered a fixed percentage for the most part, but inertial losses vary with horsepower.

numbers like 12-15 percent are used a lot to describe losses that are not that simple.

numbers like 20-25 percent are thrown around for automatic transmissions. while a 4wd truck can have losses greater than 25percent.

a 300hp f-150 can put out as low as 225rwhp.
a 305hp(underrated) mach1 290ish rwhp.
300hp 05 GT 269rwhp
lapped and polished rear end gears can drop frictional losses by a few percent. lower weight synthetic fluids help also.

Im kind of new to cars but theres one thing thats been bugging me since joining this forum.... How does HP translate into RWHP? I thought if a rear wheel drive car had 500 horse power, it would also have 500 rear wheel horse power but i guess not so much?

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Im kind of new to cars but theres one thing thats been bugging me since joining this forum.... How does HP translate into RWHP? I thought if a rear wheel drive car had 500 horse power, it would also have 500 rear wheel horse power but i guess not so much?

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Bill explained it well. Since you are new, don't get too caught up in dyno numbers. It's just a tuning tool and also to get a baseline of what the car is doing. Dyno's will vary(mustang,dynojet, land&sea, etc), each brand will vary within itself slightly. Different dyno's take different variables in to effect. Generally, the mustang dyno will dyno slightly less than a dynojet. Then, racing a car is a whole nother story. Never take a dyno for how fast a car is at the track.

my car already has gears. the immediate goal is to get 11's on drag radials and bolt-ons. i have no doubt the first time i run it with DR's i will get near the 12.5 of their car. depending on conditions.